In known articulated boom constructions, one or more arms, attached to each other in succession, are slewed by a hydraulic cylinder. A fulcrum pin connection is used to attach the arms, which allows adjacent arms to slew on one level with respect to each other. Usually, the arms are rigid and the farthest one, as viewed from the driving machine, is furnished with a device adaptable to carry out jobs. In addition to the rigid arms, there are telescopically extendable arms by which the reach is increased.
The above presented prior boom solutions lack the convertibility which is required when a multi-arm boom of an excavator is converted into loader use, in which mainly one arm is needed. It is, of course, possible to carry out loading with an excavator, but moving with a heavy load is difficult, since the load must be carried and supported by long arms which are far from the driving machine, which must rest on its wheels or tracks. On loading or lifting, the load must be brought as close to the driving machine as possible at least during the time of transportation.